The mechanism by which Bdellovibrio species breach their prey cell's cytoplasmic membrane will be examined. A number of both prokaryotic and eurkaryotic parasites are known to be capable of inserting a parsite- derived protein into the cytoplasmic membrane of their host. In some instance, this translocated protein may play a significant role in the mechanism of parasitism. The interaction of the bdellovibrios with their prey cell may be used as a model for studying such interactions. Preliminary data indicates that the bdellovibrios are able to translocate a protein into the bdelloplast cytoplasmic membrane, and this protein co- migrates on SDS-PAGE gels with OmpF, a major E. coli outer membrane porin. The source and structure of the translocated protein will be used as prey to determine if there is a specific Omp required for translocation. Using radioactive labels, the source of the translocated protein will be studied, as well as the kinetics of its insertion into the bdelloplast cytoplasmic membrane. Once the source and structure of the protein has been determined, its localization microscopy and monoclonal antibodies tagged wit protein A-colloidal gold complexes.